Microsoft have just released there Remote connectivity Analyzer tool this allows you to perform testing of your Exchange 2007 services remotely from a web page !
Allows you test ActiveSync, Autodiscovery, Outlook Anywhere connectivity and inbound mail too. Very useful for testing your configuration is setup correctly but can also be used for testing after maintenance has been performed on Exchange to confirm it’s all working correctly etc
https://www.testexchangeconnectivity.com/
More information can be found here : http://msexchangeteam.com/archive/2009/03/25/450908.aspx